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Old 04-28-2013, 08:54 PM
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I think this is interesting enough and common enough to do a DynoSim on......
This will be a street motor that will run on cat-pee regular pump gas and make excellent torque and good power to pull a heavy car around town.
The GM production 441 cast iron cylinder heads are 155cc intake runners, 62cc exhaust runners and 76cc combustion chambers.
Here's the head flow from Stan Weiss, using a pipe on the exhaust....

We'll do the standard routine of checking the main bearing bore for being parallel and round on all holes. Correct by align-hone or align-bore process. Register cylinder block on main saddle and cut decks to 9.012" block deck height. Bore and hone block for +0.030" pistons. Hone the bores with the proper grit number stones for the ring material that will be used.

We'll use Summit #SUM17350-30 hypereutictic pistons because of their very reasonable price, 1.560" compression height and excellent shelf area on the crown to form a good squish up against the underside of the cylinder head.

When used with a 0.012" piston deck height, GM 10105117 head gaskets and the piston's 6cc crowns, the 76cc cylinder heads will produce a static compression ratio of 9.06:1.
The stack of parts with 5.7" rods and 1.560" pistons equals 9.000".

I tried half a dozen different cams in this exercise, advancing them and retarding them for best hp and torque. I did not look for a lopey idle, because a lopey idle means nothing to me. It is simply the sound of a motor being inefficient. The camshaft that I chose will give us a good, steady idle and useable power from idle on up to max revs and will work well with a stock torque converter and road gears. Here's the description from Crane.......

Excellent low end torque and HP, smooth idle, daily usage, off road, towing, economy, also mild turbocharged, marine applications: primarily used in 305 and 350 near-stock engines for mild performance applications in heavy boats, OK for through-prop exhaust, 2200-2600 cruise RPM, 8.0:1 to 9.5:1 compression ratio advised.
Grind number Z-256-2
Operating range 1200-5200 rpm's
Part number 113501*o
Use Crane lifters 99277-16 and Crane springs 99848-16
Advertised duration 256/268
0.050" tappet lift duration 206/218
Cam installed 4 degrees retarded on these 0.050" numbers.....
IO (-8) BTDC
IC (34) ABDC
EO (42) BBDC
EC (-4) ATDC
Intake centerline 111
Exhaust centerline 113
Lobe separation angle 112
Dynamic compression ratio 8.03:1

Use the 600 CFM carburetor. These heads and cam will not support more carburetor. Made another 4 hp and 2 ft/lbs of torque with a 700. Not worth changing.

Use an Edelbrock Performer RPM intake manifold and 1 1/2" long-tube headers. Those cheezy shorties will hurt power, use the long tubes. The smaller 1 1/2" primaries will help low and mid range torque, the whole reason for this motor in the first place.


Max volumetric efficiency 82.9% @4000 rpm's
Max BMEP 171.5 lbs @3500 rpm's

Note to the OP: 288 is way too much cam for this low compression ratio motor. I know you want rump-rump, but this is not the motor to do it with. If you want rump-rump, build another motor with more static compression ratio that will support more cam.

Last edited by techinspector1; 04-28-2013 at 09:11 PM.
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